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Phenotypic Variability and Female Mate Choice in the Brook Stickleback, Culaea Inconstans

出版	Library and Archives Canada = Bibliothèque et Archives Canada, 2009
ISBN	04945568629780494556863
URL	http://books.google.com.hk/books?id=rFXmZwEACAAJ&hl=&source=gbs_api

註釋Understanding how variation in communication signals is manifested across a species, and how organisms use such signals to discriminate among potential mates, is crucial to understanding how behavioural mechanisms drive or maintain reproductive isolation between populations, and ultimately, speciation. In this body of research I used a molecular phylogenetic framework as a baseline context to evaluate contemporary patterns of divergence in male and female phenotypic attributes potentially used in sexual communication in two lineages of a widespread North American fish, the brook stickleback (Culaea inconstans). My results show that (1) the patterns of genetic and phenotypic variation are largely incongruent across the species range, suggesting that a complex relationship exists between genes, morphology and behaviour in this species, and that (2) pre-mating isolation between the lineages based on visual cues is likely incomplete; strong conservation of female mate assessment strategies---in particular a preference for more vigorously courting males---coupled with uncorrelated divergence in male courtship performance generated asymmetric patterns of assortative mate choice across the lineage divide during preliminary reciprocal mate choice tests. Surprisingly, variation in the linear intensity of one of the most dramatic courtship traits, male nuptial colour, had little influence on female choice decisions and no evidence of predictive relationships between the intensity of male colouration and least two female reproductive benefits (the level of male parental care and early offspring performance) were found. However, female responses to the male nuptial colour signal were strongly influenced by the spectral nature of the surrounding media, suggesting that signal structure has been largely driven by selection based on recognition and detection in a heterogeneous environment. The present findings indicate that sexual communication in the brook stickleback differs substantially from that of closely related stickleback species, and emphasizes the importance of examining geographic divergence in both female preferences and male communication signals in studies designed to elucidate the mechanisms driving, or constraining, reproductive isolation between groups.